Substrate dividing method

Abstract

A substrate dividing method which can thin and divide a substrate while preventing chipping and cracking from occurring. This substrate dividing method comprises the steps of irradiating a semiconductor substrate 1 having a front face 3 formed with functional devices 19 with laser light while positioning a light-converging point within the substrate, so as to form a modified region including a molten processed region due to multiphoton absorption within the semiconductor substrate 1 , and causing the modified region including the molten processed region to form a starting point region for cutting; and grinding a rear face 21 of the semiconductor substrate 1 after the step of forming the starting point region for cutting such that the semiconductor substrate 1 attains a predetermined thickness.

The invention claimed is: 
     
       1. A method of manufacturing a semiconductor chip, the manufacturing method comprising steps of:
 irradiating internal locations inside of a semiconductor wafer with laser light, thereby forming a plurality of modified regions along each line of a plurality of intersecting cutting lines arranged in a grid, the semiconductor wafer having a plurality of functional elements formed on a front face of the semiconductor wafer; 
 grinding a rear face of the semiconductor wafer after formation of all of the modified regions, wherein after completion of the grinding step, a fracture extending from each modified region in a thickness direction of the semiconductor wafer reaches the rear face of the semiconductor wafer; 
 chemically etching the rear thee of the semiconductor substrate, thereby forming a plurality of chamfers along each of the plurality of cutting lines arranged in the grid; and 
 dividing the semiconductor wafer, wherein the semiconductor wafer is divided when a fracture from each modified region reaches the front face and the rear face of the semiconductor wafer, thereby providing at least one manufactured semiconductor chip. 
 
     
     
       2. The method of manufacturing a semiconductor chip according to  claim 1 , wherein the chamfers form V-shaped surfaces along each of the cutting lines. 
     
     
       3. The method of manufacturing a semiconductor chip according to  claim 1 , wherein the chamfers comprise angled surfaces facing in at least four different directions. 
     
     
       4. The method of manufacturing a semiconductor chip according to  claim 1 , wherein the dividing step comprises dividing the semiconductor wafer by expanding an expanding film attached to the rear face of the semiconductor wafer. 
     
     
       5. The method of manufacturing a semiconductor chip according to  claim 1 , wherein the method comprises a step of attaching a protective film on the front face of the semiconductor wafer before forming the plurality of a modified regions.